1) Phospholipids make up cell membranes and have a hydrophilic head and hydrophobic tails which allow them to be selectively permeable. 2) Diffusion and osmosis move molecules across membranes from high to low concentration without energy. Osmosis is the diffusion of water through a membrane. 3) Active transport uses energy to move molecules against their concentration gradient using carrier proteins like the sodium-potassium pump. 4) Endocytosis and exocytosis transport larger particles and liquids in and out of cells.

1. Chapter 5 – Homeostasis and
Cell Transport

2. Pictured below is a phospholipid, which is the
lipid that makes up the cell membrane. It
consists of a polar head and two non-polar
tails. Phospholipids differ from triglycerides
because they have _________________
Two
fatty acids instead of ________________.
Three

3. Phospholipids
Phospholipid heads are
_______________, or water-
hydrophilic
loving, so they want to be near
the water. The fatty acids are
____________, or water-
hydrophobic
fearing, so they orient
themselves away from water.

4. Hydrophilic Outside Cell (watery solution)
Head
Tail
Hydrophobic
Inside Cell (watery cytoplasm)
Hydrophilic

5. Phospholipids
The cell membrane is
selectively
_______________ permeable,
because it allows some things but not
all things to pass through it.
CO2
Molecules like _____________,
_____________ and
H2O
O2
_______________ move easily
across the membrane from where
they are more concentrated to where
they are
less concentrated. This is called
diffusion
_____________________.

6. Diffusion of Sugar

7. Diffusion
When the concentration of the solute is the same on
both sides of the membrane,
___________________ is reached; however,
equilibrium
particles of a solution will continue to move
across the membrane in both directions.

8. Osmosis
The diffusion of _______ through
water
a selectively permeable membrane.

9. Osmosis
The overall movement of water is determined by
the concentration of solutes on either side of
the membrane. Wherever the solute is
more
______concentrated, it “steals” water in that
direction!!
*A simple trick to use to remember this concept is: Solute Steals!
I STEAL
H 2O!

10. Hypotonic
 less
The word "HYPO" means _________
 Hypotonic environment: lower solute
(salt) concentration than cell=
swell
cells________
 In animal cells, this may cause the cell to
burst, as is the case with red blood cells.
cytolysis
This is called ____________.

11. Hypotonic (con’t)
 Some organisms, like the
paramecium
___________________, are
able to collect excess water and
pump it out of the cell, which
requires energy.
 Video of Contractile Vacuole

12. Hypotonic (con’t)
 Plant cell are often in and
able to survive in a hypotonic
environment. In plant cells,
the central vacuole will fill
with water and put pressure
on the plant, which is called
turgor pressure
___________________.
 The cell wall keeps the plant
bursting
from _______________

13. Hypertonic
 The word "HYPER" means
more.
 Hypertonic environment:
higher solute (salt)
concentration than cell=
shrink
cells________________.
 In plant cells, the central
vacuole loses water and the
cells shrink, causing wilting
which is called
plasmolysis
_____________.

14. Isotonic
 "ISO" means the same
 Isotonic environment: equal solute (salt)
no effect
concentration as cell= __________on cell.
equally
 Water moves __________ in both
directions.

15. Osmosis Question #1
 In cherry-producing areas of the U.S.,
rainfall at a critical time in the ripening
process can have a devastating effect on
the harvest. Pure rainwater on a ripe-sugar
filled cherry will begin to diffuse inward,
causing the cherry to swell and split, and
ruin the fruit. What environment is this
cherry in?

16. Question #1 (con’t)
 To fix this, orchardists have begun spraying
their water-soaked cherry trees with calcium
chloride in order to reverse this process and
prevent fruit splitting. What environment
would they be in now?

17. Osmosis Question #2
 Carrot sticks in Water
 Predict what environment (hypertonic,
hypotonic, isotonic) a carrot will be in when it
is placed in:
A. Distilled:
B. Tap Water:
C. Salt Water:

18. Osmosis Question #4
 What environment would strawberry cells be
in when you sprinkle sugar on them?

19. Osmosis Question #4
Your dad is preparing a vegetable
tray for a party. He discovers
that the celery in the refrigerator
is no longer crisp. How could he
make the celery crispy and
crunchy?

20. Facilitated Diffusion
Some molecules are too large to pass through
the pores in the membrane, or they are not
soluble in lipids. These molecules, such as
glucose and amino acids, diffuse by way of a
_________________ protein. Molecules still
channel
move from high to low concentration, so no
energy is needed

21. Facilitated Diffusion

22. Transportation Requiring Energy
Some ions and molecules need a
special pump to get them across
the membrane. This is because
they are moving from an area
less
where there is _______________
of them to an area there is
more
__________ of them.
This is called
Active Transport
___________________

24. Transportation Requiring
Energy
One type of active transport is called the
Sodium-Potassium pump which helps muscle
____________
cells contract. This pump uses _________ to
energy
move ions from where there are few of them
to where there aremany
________ of them. The
protein that is used to pump the ions through
carrier
is called a _____________ protein and it
changes its _______________ to move the
Shape
ions across the cell membrane.

25. Sodium-Potassium Pump
Animation

26. Sodium-Potassium Pump
People drink sports drinks when they exercise
to replace some of the sodium and
potassium ions that are important for this
pump. Without these ions you would get a
cramp.

27. Endocytosis & Exocytosis
Larger molecules, solid clumps of food,
liquids, and even whole cells can be
transported by infoldings, or pockets, of the
cell membrane.
Phagocytosis
 ________________, or “cell eating” requires
extensions of the cytoplasm surrounding a
particle and packaging it within a food vacuole.

28. Phagocytosis

29. Endocytosis
 Pinocytosis
_________________, or “cell drinking”,
occurs when tiny pockets form along the cell
membrane, fill with liquid and pinch off to
form vacuoles within the cell.

30. Exocytosis
 Exocytosis
________________ involves removing
material like water and or waste form the
cell.

31. Endocytosis AND
Exocytosis require energy.

32. To summarize:
Passive transport:
simple diffusion,
osmosis, facilitated
diffusion
Active transport:
pumps, endocytosis
(phagocytosis,
pinocytosis),
exocytosis